#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef double db;

#define in read()
#define pii pair<int,int>
#define fi first
#define se second
#define FILE(x) freopen(x".in","r",stdin);\
	freopen(x".out","w",stdout);
#define pb push_back

int read(){
	int x = 0,sgn = 1;char ch = getchar();
	for(;!isdigit(ch);ch = getchar()) if(ch == '-') sgn = -1;
	for(;isdigit(ch);ch = getchar()) x = (x<<1)+(x<<3)+(ch^48);
	return x*sgn;
}

const int N = 1e5+10;

int cnt = 1,h[N],deg[N],n,m,k,now[N];
struct edge{int v,nxt;}e[N<<4];
bool vis[N<<4];
vector<pii> ans;
void link(int x,int y){e[++cnt] = (edge){y,h[x]};h[x] = cnt;}

void dfs(int x){
	for(int i = now[x];i;i = e[now[x]].nxt){
		now[x] = i; if(vis[i]) continue; vis[i] = vis[i ^ 1] = 1;
		dfs(e[i].v);
		if(++k & 1) ans.pb(pii(x,e[i].v)); else ans.pb(pii(e[i].v,x));
	}
}

int main (){
#ifndef ONLINE_JUDGE
	freopen("1.in","r",stdin);
#endif
	n = in,m = in;
	for(int i = 1,u,v;i <= m;i++){
		u = in,v = in; link(u,v); link(v,u); deg[u]++; deg[v]++;
	}
	int lst = 0;
	for(int i = 1;i <= n;i++) if(deg[i] & 1) {if(!lst) lst = i;else link(lst,i) , link(i,lst) , lst = 0 ,m++;}
	if(m & 1) link(1,1);
	for(int i = 1;i <= n;i++) now[i] = h[i];
	dfs(1); printf("%lu\n",ans.size());
	for(pii x : ans) printf("%d %d\n",x.fi,x.se);
	return 0;
}
